1. Technical Field
The present invention relates to a liquid crystal display device and an electronic apparatus.
2. Related Art
In the related art, there is known a technique in which a liquid crystal shutter device is disposed on an illumination unit side of a transmission type liquid crystal panel to thereby adjust light incident on the transmission type liquid crystal panel (reference should be made to, for example, JP-A-9-073070, JP-A-2004-283548, and JP-A-2006-141559).
The liquid crystal shutter device includes a liquid crystal layer sandwiched between a pair of electrodes. A polymer dispersion type liquid crystal layer is an example of the liquid crystal layer used in the liquid crystal shutter device. The polymer dispersion type liquid crystal layer contains liquid crystal molecules and polymers. The polymer dispersion type liquid crystal layer is formed by causing a mixture of polymeric precursors and liquid crystal molecules to be disposed between a pair of electrodes and then, irradiating the mixture with energy. The polymeric precursors are polymerized by the energy irradiation to be changed into polymers, and the polymers are phase-separated from the liquid crystal molecules.
The polymer dispersion type liquid crystal layer is classified into a reverse type and other types depending on presence or absence of its alignment state under a non-electric field application state. In a reverse type polymer dispersion type liquid crystal layer, polymers and liquid crystal molecules are aligned together with each other in the non-electric field application state. In the reverse type polymer dispersion type liquid crystal layer, the polymers are formed with liquid crystal monomers as the polymeric precursors. By causing the liquid crystal monomers to be polymerized in an aligned state, aligned polymers are obtained. Since the polymers per se are aligned, the polymers exert an alignment regulating force of aligning the liquid crystal molecules.
In the reverse type polymer dispersion type liquid crystal layer, since the refractive index of the polymers and the liquid crystal molecules in the non-electric field application state are constant or change continuously, the polymer dispersion type liquid crystal layer operates in a non-scattering mode where incident light is emitted without being scattered. Moreover, in an electric field application state, an alignment direction of the liquid crystal molecules is changed by the electric field, the refractive index is discontinuous between the liquid crystal molecule portion and the polymer portion. Therefore, the polymer dispersion type liquid crystal layer operates in a scattering mode where incident light is emitted in a scattered manner.
In an image display device disclosed in JP-A-9-073070, a reverse type liquid crystal shutter device is used for adjustment of a viewing angle. Light emitted outside a predetermined viewing angle is scattered by the liquid crystal shutter device so that an image represented by the light is not visually perceived.
In a game machine disclosed in JP-A-2004-283548 and JP-A-2006-141559, a liquid crystal shutter device is used for switching of displays by a display unit of the game machine. Light representing a base image is incident on a liquid crystal panel via the liquid crystal shutter device, is appropriately modulated therein, and is emitted from the display unit. In a non-scattering mode of the liquid crystal shutter device, the light representing the base image is passed through the liquid crystal shutter device without being scattered, whereby the base image is displayed to be overlapped with an additional image by the liquid crystal panel. In a scattering mode of the liquid crystal shutter device, the light representing the base image is passed through the liquid crystal shutter device in a scattered manner, whereby only an image by the liquid crystal panel is displayed. In this manner, in the game machine disclosed in JP-A-2004-283548 and JP-A-2006-141559, it is possible to display images with plenty of expressiveness by the display unit, and to thus provide versatile presentations.
However, in such a display unit as disclosed in JP-A-2004-283548 and JP-A-2006-141559, it is generally considered that the liquid crystal shutter device is mainly used in the non-scattering mode. This is because in the scattering mode, the expressiveness of the display unit is not sufficiently exhibited since the base image is not displayed. If the non-scattering mode is mainly used, the period in which the liquid crystal shutter device is used in the scattering mode becomes longer than the period in which it is used in the non-scattering mode.
In such an electronic apparatus, it is considered good to use a reverse type liquid crystal shutter device as in the case of JP-A-9-073070. This is because according to the reverse type liquid crystal shutter device, since it operates in the non-scattering mode under the non-electric field application state, the consumption power of the liquid crystal shutter device becomes small and deterioration in alignment property with driving is suppressed, and thus, the operating life of the liquid crystal shutter device can be increased.
However, when the reverse type liquid crystal shutter device is applied to such a display unit as disclosed in JP-A-2004-283548 and JP-A-2006-141559, the following disadvantages may be caused.
In the reverse type liquid crystal shutter device, the alignment direction of the polymers does not change depending on presence or absence of electric field application. Therefore, a portion of light incident on the liquid crystal shutter device might be emitted without being scattered irrespective of presence or absence of electric field application, so that leakage light may be emitted from the liquid crystal shutter device in the scattering mode. As a result, a portion of the base image may be displayed by the leakage light during a non-display period of the base image, whereby display quality is deteriorated.
Moreover, in the image display device disclosed in JP-A-9-073070, by the same reasons, there is a disadvantage that images may be visually perceived from outside a predetermined viewing angle.